The present invention relates to a method for manufacturing natural cheese. More particularly, the present invention provides a method for incorporating concentrated milkfat into milk which can be used in the preparation of natural cheese. The method of incorporating the concentrated milkfat into milk helps insure that loss of milkfat during manufacture of the natural cheese is minimized.
Natural cheeses are produced by combining various, but specific, ingredients to produce a resultant cheese. Natural cheeses are generally made by developing acidity in milk and setting the milk with a clotting agent, such as rennet, or by developing acidity to the isoelectric point of the protein. The set milk is cut and whey is separated from the resulting curd. The curd may be pressed to provide a cheese block. Curing typically takes place over a period of time under controlled conditions. Natural cheeses do not contain added emulsifiers and/or stabilizers.
Natural cheeses are distinct from processed cheeses, which are a cheese product manufactured by combining a natural cheese with other ingredients. Processed cheeses are produced by processing (e.g., grinding) natural cheese and then mixing the prepared natural cheese with emulsifying agents (e.g., emulsifying salts). Typically, the resulting mixture is heated and worked to produce a homogenous mass of processed cheese. Accordingly, a processed cheese is literally a natural cheese which has subsequently been processed.
An important step in producing natural cheeses is to provide a milk/milkfat blend with a desired fat level. One method for providing such a milk/milkfat blend is to blend concentrated milkfat with milk to provide a blend with the desired fat level. Concentrated milkfat must be thoroughly mixed with milk and/or cream at proper ratios to prevent the occurrence of defects in the final cheese product. Further, a concentrated milkfat/milk blend must be mixed in a manner effective for preventing fat separation during additional processing steps. Prior to this invention, it has not been possible to use concentrated milkfat/milk blends to prepare natural cheeses.
Regulations governing the production of natural cheeses preclude the use of stabilizers in the milk to prevent fat separation. Accordingly, a cheese-maker must rely on proteins normally present in the native milk to act as emulsifiers for any non-native fat added to the process. In this regard, native protein in the milk and non-native fat must be brought together under certain homogenization conditions to prevent fat separation during additional processing. Current methods for incorporating concentrated milkfat into a milk stream relies on the use of piston-type homogenization. Due to high pressures and moving parts, piston-type homogenizers are capital intensive and difficult to maintain. Moreover, it is difficult to consistently obtain particle size distributions similar to that of natural milk.
It would be desirable, therefore, to provide less expensive methods to incorporate fat, especially milkfat, into milk for use in the manufacture of natural cheese. It would also be desirable, therefore, to provide methods to incorporate fat, especially milkfat, to provide milk substrates having particle size properties essentially the same as natural milk and which can be used in the manufacture of natural cheese. The present invention provides such methods.
The present invention is directed to a method for incorporating concentrated milkfat (generally greater than about 70 percent fat) into milk to form a concentrated milkfat/milk blend or substrate which can be used in the preparation of natural cheese. The invention provides a cost effective method for blending concentrated milkfat and milk without the use of added stabilizers. This invention is also directed to a method for the production of natural cheese using a milk substrate prepared from a concentrated milkfat and milk blend. In an important aspect of the invention, the method is effective for providing a concentrated milkfat/milk blend or substrate where fat does not separate during additional processing required in producing natural cheese.
The cost of milkfat, either in the form of cream (fat content of about 18 to 45 percent fat) or concentrated milkfat (fat content of greater than about 70 percent fat), can vary significantly through the year. Generally, the cost is lower in the first half of the year and higher in the second half. For example, the maximum cost of concentrated milkfat in the second half of the year is often as much as 50 percent higher than the minimum cost in the first half. Thus, it would be very advantageous to collect and store milkfat during period of low cost for use at other times of the year. Concentrated and frozen milkfat can be stored for extended periods (generally at least about 12 months), thereby making it an excellent vehicle for storing milkfat for later use. Unfortunately, it has not been possible to use such concentrated milkfat for preparing natural cheeses since stabilizers have been required to form milk substrates using concentrated milkfat.
Since stabilizers are not allowed in natural cheese under the current Standards of Identity, it has not been possible to prepare natural cheeses using concentrated milkfat/milk blends. This present invention provides a method for preparing concentrated milkfat/milk blends without the use of added emulsifiers and/or stabilizers. Using such concentrated milkfat/milk blends, natural cheeses can now be prepared which are virtually identical to natural cheeses prepared from natural milk. Using this invention, milkfat can be collected and stored as concentrated milkfat during periods of low cost for later conversion to natural cheeses. Moreover, during periods of high milkfat cost, full-fat milk can be skimmed, the cream sold for other uses, and milkfat replaced using concentrated milkfat to produce a milk substrate that can be used to prepare natural cheeses, thereby increasing the overall efficiencies and economic return associated with the production of natural cheese.
In one embodiment of the present invention and is generally illustrated in FIG. 1, native fat in raw milk is reduced to provide a reduced-fat raw milk containing less than about 3 percent fat and preferably a skim milk containing about 0.05 to about 2 percent fat. The resulting cream can be sold as is or used in other products. A first portion of the reduced-fat raw milk is heated to about 125 to about 145xc2x0 F. and concentrated milkfat (or other fat), preferably in the form of relatively small particles, is added to the milk at a level of about 4 to about 10 percent to form a slurry. The slurry is maintaining at this elevated temperature until all of the concentrated milkfat has melted. The slurry is homogenized to obtain a concentrated milkfat/milk blend or substrate containing fat particles having an average particle size and a particles size distribution similar to natural milk. More specifically, the fat particles in the substrate have an average diameter of about 1.0 to about 10.0 microns and a particle size distribution such that at least about 90 percent of the fat particles in the substrate should have diameters of about 1.0 to about 10.0 microns. More preferably, the fat particles in the substrate have an average diameter of about 1.0 to about 5.0 microns and a particle size distribution such that at least about 90 percent of the fat particles in the substrate should have diameters of about 1.0 to about 5.0 microns. Preferably the homogenization is effected using a jet homogenizer, and more preferably an in-line jet homogenizer, at a pressure of about 90 to about 200 psig.
The resulting milkfat/milk blend may be used for the production of natural cheese using conventional procedures. More preferably, the resulting milkfat/milk blend, after pasteurization and cooling (preferably to below about 100xc2x0 F.), is blended with additional pasteurized reduced-fat milk (also preferably cooled to below about 100xc2x0 F.), in a final blending step to form a standardized blended substrate which is then used for the production of natural cheese. Preferably and as illustrated in FIG. 1, the additional reduced-fat milk, preferably skim milk, is also obtained as a second portion of the reduced-fat milk treated in the separator. Preferably, the resulting standardized blended substrate formed in the final blending step contains about 25 to about 50 percent milkfat/milk blend (i.e., the first portion from the separator) and about 50 to about 75 percent reduced-fat milk (i.e., the second portion from the separator), and even more preferably, about 25 to about 35 percent milkfat/milk blend and about 65 to about 75 reduced-fat milk. Importantly, the fat droplet size of the resulting milkfat/milk blend and/or the standardized blended substrate, is sufficiently small such that fat loss is minimized during the manufacture of the desired natural cheese.
Another embodiment of the present invention is illustrated in FIG. 2. This embodiment differs from the first embodiment discussed above mainly in that the reduced-fat milk of portions 1 and 2 need not be taken directly from a cream separator and that the reduced-fat milk of portions 1 and 2 need not be taken from the same source and can, if fact, be different starting materials. Thus, for example, the reduced-fat milk starting materials for portions 1 and 2 can differ, if desired, in fat content, protein content, and the like. Like the first embodiment, the resulting standardized milk substrate can be used to prepare natural cheese using conventional cheese-making techniques.